Not 24/7, but I carry a FB all the time when I'm not in SF dressed for office work or otherwise engaged at some formal or semi-formal affair.
If I'm camping, it's usually something in the 4"-6" (blade length) range, either a Livesay Air Assault, Mora2000 or Wesolowski (If I'm being ultra-lite), or lately my E. Chang heavy hunting knife. At home and around town, its more like 2.5"-4", typically a Dozier K1, my Taz custom long B&T, or one of a couple of other hand made knives I have from M. Wesolowski, D. Fraley, B. Posner, or the Chang again! I have lots of options...
When I go into town around here, I try to limit the size to 3" and something with a relatively discrete sheath that doesn't stand out too much. In another month I'm picking up a small 2.5" blade knife from Ron Clark for exactly this purpose. Now its mostly the Dozier K1, or the Fraley or Posner. All of the others draw a little to much attention to themselves...